1. Field of the Invention
The present invention relates to an endoscope light source unit suitable for an endoscope and/or an electronic endoscope, etc.
2. Description of the Related Art
Recent electronic endoscope systems have been provided therein with a processor having a built-in light source unit for lighting, to which an electronic scope, having an electronic camera mounted on the distal end thereof, or a fiber scope for conducting observation only through optical members, is connected for use. In particular, electronic scopes, with a wide variety of thicknesses and functions suited to different locations of observation, have been provided for use. Processors connectable with various types of electronic scopes and fiber scopes must also have light source units that are compatible with such various electronic scopes and fiber scopes. For this reason, conventional light source units have been constructed to be capable of supplying necessary amounts of illumination light to electronic scopes that require a maximum light quantity.
Such light source units are configured such that illumination light emitted from a high-intensity lamp is condensed by a condenser lens and made incident on the incident end face of a scope light guide, typically an optical fiber bundle. Since the necessary quantity of illumination light varies in accordance with the type of electronic scope and with the observation location, the light source units are equipped with an aperture device for mechanically adjusting the amount of light. Among known aperture devices is one that includes a diaphragm which is composed of a partly-notched portion and an arm portion integrated with the partly-notched portion, having a size such that all the light from a light source lamp can be blocked, and a motor mechanically connected to an end of the arm portion. The motor is rotated to turn the diaphragm about the top of the arm portion, thereby changing the degree of illumination light blocked by the partly-notched portion to adjust the illumination quantity (see Japanese Patent Laid-Open Publication No. 2003-305008). Moreover, a light shielding disk may be provided with a plurality of aperture openings having different opening ratios or transmittances (hereinafter collectively referred to as “opening ratios”) so as to form a rotary aperture disk (rotary aperture plate) which regulates the amount of light incident on the incident end face of a light guide by putting one of the aperture openings selectively between a light source unit and the incident end face of the scope light guide (i.e., into the illumination optical path). This rotary aperture disk is rotated so that one of the aperture openings whose opening ratio is appropriate to the connected scope is positioned into an optical path of the light source unit, and is held at this rotation position for use.